21603899 has 2 divisors, whose sum is σ = 21603900. Its totient is φ = 21603898.

The previous prime is 21603871. The next prime is 21603917. The reversal of 21603899 is 99830612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21603899 - 2⁸ = 21603643 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21603859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10801949 + 10801950.

It is an arithmetic number, because the mean of its divisors is an integer number (10801950).

Almost surely, 2^21603899 is an apocalyptic number.

21603899 is a deficient number, since it is larger than the sum of its proper divisors (1).

21603899 is an equidigital number, since it uses as much as digits as its factorization.

21603899 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21603899 is about 4647.9994621342. Note that the first 3 decimals coincide. The cubic root of 21603899 is about 278.5120860038.

The spelling of 21603899 in words is "twenty-one million, six hundred three thousand, eight hundred ninety-nine".